(1) Field of the Invention
This invention relates to a method for continuous synthesis of highly pure monoglyceride utilizing an enzymatic reaction.
(2) Prior Art
Heretofore monoglycerides have mainly been synthesized by either a batch method or a continuous method. Batch methods in which glycerin and a fatty acid are stirred with heating in the presence of a chemical catalyst or an enzyme have the advantage of high reaction rate but have the disadvantage that the catalyst (or enzyme) is hard to isolate after the reaction. On the other hand, according to continuous methods, a reaction mixture consisting of glycerol and a fatty acid is stirred in or passed through a reactor containing an enzyme immobilized on a thin film or a solid carrier to carry out the esterification reaction. These continuous methods have the advantage that the enzyme can be repeatedly and safely used for a long time, but have disadvantages in that (i) the contact area for the reaction is inadequate, (ii) reaction rate is lowered because of loss or lowering of activity at immobilization and (iii) the cost of immobilizing agents is high and the like. Further, when a chemical catalyst is used, esterification proceeds regardless of whether the used fatty acid is of straight-chained or branched structure, and in a case where there is no need for branched fatty acid monoglycerides, the cost for purification of monoglycerides is high.
Furthermore, even when an enzyme which preferentially synthesizes monoglycerides is used in batch methods or continuous methods, it is impossible at present to synthesize monoglycerides alone. Thus, no method for continuously and effectively obtaining highly pure monoglycerides has been known.